<select name="form[khet_id]" id="form_khet_id_" onchange="getDistrictByProvinceID()">
    <option value="0">ทุกเขต</option>
    <option value="1">เขต1</option>
    <option value="2">เขต2</option>
    <option value="3">เขต3</option>
</select>
